Purification of cyclic olefinic ketones



Patented Mar. 29, 1949 UNITED STATES TENT OFFICE PURIFICATION OF CYCLICOLEFINIC KETONES No Drawing. Application August 6, 1945, Serial No.609,324

9 Claims. (Cl. 260-586) This application is a continuation-in-part ofour co-pending application Serial No. 570,466, filed December 29, 1944,now abandoned.

This invention relates to an improved process for purifying cyclicolefinic ketones, particularly when the latter are present in admixturewith products formed incidental to the preparation of said cyclicketone.

An object of this invention is an improved process for separating acyclic olefinic ketone from a mixture consisting of an aliphaticolefinic ketone and a cyclic olefinic ketone.

Another object of this invention is an improved process for removingaliphatic olefinic ketones from a mixture of alkyl ketone condensationproducts including aliphatic olefinic ketones and cyclic ketones.

A further object of this invention is to provide an improved process forseparating mesityl oxide and phorone from isophorone present in amixture of condensation products of acetone.

One specific embodiment of the present invention relates to a processfor separating cyclic olefinic ketones from aliphatic olefinic ketoneswhich comprises treating a mixture of said cyclic and aliphatic olefinicketones with an aqueous solution of an acid-acting salt at a temperatureof from about 100 to about 350 C. to convert aliphatic olefinic ketonesinto alkyl ketone, and separating said alkyl ketone from unconvertedcyclic olefinic ketone.

Another embodiment of this invention relates to a process whichcomprises condensing an alkyl ketone to form a reaction mixturecomprising essentially a cyclic olefinic ketone and an allphaticolefinic ketone, treating said reaction mixture with an aqueous solutionof an acid-acting salt at a temperature of from about 100 to about 350C. to convert said aliphatic olefinic ketone into alkyl ketone,separating said alkyl ketone from unconverted cyclic olefinic ketone,and recycling said alkyl ketone to further condensation treatment.

A further embodiment of this invention relates to a promss for treatinga mixture of condensation products of an alkyl ketone with an aqueoussolution 01 an acid-acting salt at a temperature of from about 100 toabout 350 C. to convert aliphatic olefinic condensation products ofalkyl ketones into alkyl ketone, and separating said alkyl ketone fromunconverted cyclic, mono-olefinicketone condensation products of saidalkyl ketone.

A still further embodiment of the present intreating a mixture ofacetone condensation products including mesityl oxide, phorone, andisophorone at a temperature of from about 150 to about 350 C. with adilute aqueous solution of an acid-acting salt whereby said mesityloxide and phorone are converted into acetone, and separating saidacetone from unconverted isophorone.

Acetone may be condensed and cyclized to isophorone by several knownmethods, but in most of the cases a number of by-products are alsoformed including unsaturated aliphatic ketones such as mesityl oxide andphorone, Accordingly, when isophorone is the desired reaction product,the yield of this desired material is decreased by the appearance of thementioned by-products. These different by-products not only cause a lossbut they are also sometimes troublesome to dispose of in large scalecommercial operations,

We have observed that mesityl oxide and phorone are converted intoacetone by treatment at an elevated temperature in the presence of arelatively large volume of a dilute aqueous solution of an acid-actingsalt, While isophorone remains substantially unchanged during thistreatment and is recoverable from the reaction mixture in relativelyhigh purity.

While the process of our invention is particularly applicable to thepurification of isophorone derived from acetone, this process is alsoutilizable in purifying homologues of isophorone such as are obtainableby condensation of certain other ketones. An alkyl ketone which isconvertible into a homologue of isophorone has at least one hydrogenatom combined chemically with the carbon atom adjacent to the carbonylcarbon atom, while the other carbon atom adjacent to the carbonyl carbonatom is combined chemically to at least two hydrogen atoms. Thus,homologues of isophorone are formed by the condensation of such ketoniccompounds including methyl ethyl ketone, methyl propyl ketone, methylisopropyl ketone, methyl isobutyl ketone, diethyl ketone, ethyl propylketone, ethyl iso- The process of this invention is effected in thepresence of a catalyst comprising essentially an aqueous solution of anacid-acting salt. Suitable catalytic materials include particularlyaqueous solutions of magnesium chloride, aluminum chloride, ironchloride, nickel chloride, ammonium chloride, and the correspondingbromides and sulfates, The concentration of the acid-acting salt isgenerally from about 0.05 to about 10% by vention relates to a processwhich comprises weight of the total aqueous solution. The catalystspreferred for our process comprise aqueous solutions of acid-actingsalts of such concentrations that the solutions have a pH value of lessthan about 6. The volume of solution used relative to the ketonecondensation product undergoing treatment should be such that water ispresent in more than 200% of the theoretical quantity necessary forconversion of the unsaturated dimers of the alkyl ketones into saidalkyl ketones. The temperature of the reaction mixture should be fromabout 100 to about 350 C. but is preferably from about 150 to about 250C. It is also desirable to carry out the process at a superatmosphericpressure to maintain in liquid phase a substantial proportion of thereactants and solution of hydrolyzable salt.

The process is carried out by commingling a mixture of the alkyl ketonecondensation products with one or more volumes of an aqueous solution ofan aicd-acting salt at a temperature and for a time sufi'icient toconvert aliphatic unsaturated ketonic condensation products of alkylketones into said alkyl ketones with substantially no influence upon thecyclic, mono-olefinic ketones present in said alkyl keto-ne condensationproduct, Thus, when acetone condensation products comprising mesityloxide, phorone, and isophorone are so treated, the mesityl oxide andphorone are converted into acetone which is dissolved in the aqueoussolution and is readily separable from unconverted isophorone. Theacetone present in said aqueous solution may then be recovered bysuitable means and/or subjected to condensation reaction to produceadditional quantities of isophorone. The organic material from whichmesityl oxide and phorone were so separated and comprising essentiallyisophorone is then washed, dried, and distilled to give a frac-' tioncomprising substantially pure isophorone.

The following examples are given to illustrate the character of resultsobtained by the process of our invention, although these data are notintroduced with the intention of unduly restricting the broad scope ofthe invention.

Example I 49 grams of mesityl oxide and 150 grams of an aqueous solutioncontaining 2 to 3% by weight of ferric chloride were heated at 210 C.for 2.5 hours in a rotatable steel autoclave of 450 cc. capacity. Thereaction product contained acetone but no mesityl oxide, showing thatthe mesityl oxide underwent conversion into acetone.

Emample II In another run at the same temperature and operatingconditions, 30 grams of phorone when treated with an aqueous solutioncontaining 3% by weight of ferric chloride yielded 73% of acetone and27% of unconverted phorone.

Example III Example IV A mixture of acetone condensation pro-ductsconsisting of of isophorone, 25% of phorone, and 65% of mesityl oxideupon treatment with 4 4 volumes of an aqueous solution containing 3% byweight of ferric chloride at 225 C. for 1 hour yields an organic liquidproduct comprising essentially isophorone. The aqueous solution offerric chloride contains acetone in an amount Example V A mixtureconsisting of 40 grams of mesityl oxide, 15 grams of phorone and 25grams of isophorone and 125 grams of an aqueous solution containing 3%by weight of ammonium chloride was heated at 260 C. for 2 hours in arotatable steel autoclave of 450 cc. capacity. During this treatmentabout of the mesityl oxide and of the phorone were converted intoacetone.

The novelty and utility of the process of the present invention areevident from the preceding specification and examples, although neithersection is introduced to limit unduly the generally broad scope of theinvention.

We claim as our invention:

1. A process for separating a cyclic olefinic ketone from a mixturecontaining said cyclic oler'inic ketone and an aliphatic olefinio ketonewhich comprises treating said mixture with an aqueous solution of anacid-acting salt at a temperature of from about to about 350 C. toconvert the aliphatic olefinic ketone into alkyl keto-ne, and separatingsaid alkyl ketone from unconverted cyclic olef nic ketone.

2. A process which comprises treating a mixture of alkyl ketonecondensation products comprising cyclic mono-oiefinic ketones andaliphatic olefinic ketones with an aqueous solution of an acid-actingsalt at a temperature of from about 100 to about 350 C. to convert thealiphatic oleing said alkyl ketone and the unconverted cyclic,mono-oleiinic ketone.

3. A process which comprises treating a mixture of alkyl lzetonecondensation products comprising cyclic and aliphatic olefinic ketoneswith an aqueous solution of an acid-acting salt at a temperature of fromabout 100 to about 350 C. and at a superatmospheric pressure to convertthe aliphatic olefinic ketones into an alkyl ketone, and separating saidalkyl ketone and the unconverted cyclic, mono-olefinic ketone.

4. A process which comprises treating a mixture of acetone condensationproducts including mesityl oxide, phorone, and isophorone at atemperature of from about 100 to about 350 C. with a dilute aqueoussolution of an acid-acting salt to convert said mesityl oxide andphorone into acetone, and separating said acetone and unconvertedisophorone.

5. A process for preparing substantially pure isophorone which comprisestreating a mixture of acetone condensation products including mesityloxide, phorone, and isophorone with a dilute aqueous solution of anacid-acting salt at a temperature of from about 100 to about 350 C. andat a pressure suflicient to maintain the reaction mixture in liquidphase to convert said mesityl oxide and phorone into acetone, andseparating said acetone and unconverted isophorone.

6. A process for preparing substantially pure 'isophorone whichcomprises treating a mixture of acetone condensation products includingiesityl oxide, phorone, and isophorone with a dilute aqueous solution ofan acid-acting chloride salt at a temperature of from about 100 to about350 C. and at a pressure sufiicient to maintain the reaction mixture inliquid phase to convert said mesityl oxide and phorone into acetone, andseparating said acetone and unconverted isophorone.

7. A process for preparing substantially pure isophorone which comprisestreating a mixture of acetone condensation products including mesityloxide, phorone, and isophorone with an aqueous solution containing fromabout 0.05 to about 10% by weight of an acid-acting chloride salt at atemperature of from about 100 to about 350 C. and at a pressuresufficient to maintain the reaction mixture in liquid phase to convertsaid mesityl oxide and phorone into acetone, and separating said acetoneand unconverted isophorone,

8. A process for preparing substantially pure isophorone which comprisestreating a mixture of acetone condensation products including mesityloxide, phorone, and isophorone with an aqueous solution containing fromabout 0.05 to about 10% by weight of ferric chloride at a temperature offrom about 100 to about 350 C.

and at a pressure sufficient to maintain the reac- 5 tion mixture inliquid phase to convert said mesityl oxide and phorone into acetone, andseparating said acetone and unconverted isophorone. 9. A process forpreparing substantially pure isophorone which comprises treating amixture of acetone condensation products including mesityl oxide,phorone, and isophorone with an aqueous solution containing from about0.05 to about 10% by weight of ammonium chloride at a temperature offrom about 100 to about 350 C. and at a pressure sufficient to maintainthe reaction mixture in liquid phase to convert said mesityl oxide andphorone into acetone, and separating said acetone and unconvertedisophone.

HERMAN PINES. VLADIMIR N. IPATIEFF.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Name Date McAllister June 13, 1944 Number

